1. Field of the Invention
The present invention relates in general to photocoupled control apparatus for auxiliary lighting system for vehicles. In particular, the present invention relates to photo-coupled control apparatus employing light signal-coupling for the control of the auxiliary lightings of vehicles.
2. Technical Background
Auxiliary lightings for vehicles, for example, over-roof, frame-mount, or bumper-attached auxiliary lighting lamp arrays of different variety including, such as, fog lamps, utility lamps, and driving lamps, are generally installed as optional equipments for vehicles such as pick-up trucks, or jeeps, etc. These exteriorly mounted auxiliary lighting systems are not standard to the vehicles manufactured by car makers, but are rather added to the vehicle by the vehicle owner's selection, at some time after the vehicle is purchased.
For the installation of the added auxiliary lighting system, although the electrical power wiring are not required to go into the driver's cab for access when used, however, the wiring for the control of the added lighting system, for example, at least the control wiring for basic turning on and off of the lighting system must be led into the cab so that the controlling switches can readily and conveniently be within reach of the driver when the vehicle is driving along. For this requirement, a few control wirings must therefore go through the firewall that separates the driver's cab from the engine compartment, from the control unit of the added auxiliary lighting system, which is normally located in the engine compartment, to the control switches in the driver's cab.
Electrical wiring for the conventional auxiliary lighting systems involved in their installation therefore frequently requires laborious effort. This is primarily because of the fact that modern vehicles are designed with compact engine compartment, the firewall standing between the engine compartment and the driver's cab of the vehicle is well crowded with the various components that must run through the firewall. It is generally difficult to locate freely accessible holes on the firewall to arrange the necessary wiring.
On the other hand, the dashboard of a modern vehicle is also frequently crowed, with little space left for the installation of additional switches for the added auxiliary lighting system. Even if spare switch locations are available on the dashboard, they are always not easy for direct access for installation of the added switches.
In general, obvious method of adding exterior auxiliary lighting system to a vehicle involves the installation of some electrical wiring from the engine compartment to the driver's cab. A penetration of the wires through the firewall would be necessary if hard wiring of the control of the added lighting system is intended.
To avoid the problem described above, P. K. Brown proposed a wireless control for these added auxiliary lighting systems in the U.S. Pat. No. 5,195,813, titled "Wireless control for auxiliary lighting", issued Mar. 23, 1993. In Brown's disclosure, a very low power transmitter located in the driver's cab transmits simple or encoded signals to a receiver included in the control module of the added lighting system, so that the control instructions of the lighting system can be decoded to facilitate control accordingly. Although such implementation of lighting control avoids the requirement for any control wiring to actually go through the firewall, however, the radio transmitter/receiver pair still involves relatively much higher costs than the hard wired implementation.